Hyperreactive malarial splenomegaly — DTM&H MCQ

Correct answer: C — Hyperreactive malarial splenomegaly

The correct answer is C, hyperreactive malarial splenomegaly (HMS). This diagnosis is defined by Fakunle's criteria: massive splenomegaly (over 10 cm below the costal margin) in a resident of a malaria-endemic area, markedly raised IgM, strongly positive antimalarial antibody titres, and negative blood films despite the clinical picture, all of which this man has. HMS represents an aberrant B-cell driven immune response to chronic, repeated Plasmodium exposure rather than active parasitaemia, so films are typically negative while serology remains strongly positive. The absence of fever and HIV-negative status help exclude infective and lymphoproliferative mimics, and the Papua New Guinea residence fits the epidemiology of holoendemic malaria transmission that predisposes to this syndrome. Why the other options are wrong: E. Chronic myeloid leukaemia: would typically show marked leucocytosis with a left-shifted myeloid picture and basophilia on blood film, and would not explain the markedly raised IgM or positive malaria serology. A. Disseminated histoplasmosis: usually occurs in immunocompromised hosts (often HIV-positive) and presents with fever, pancytopenia and evidence of fungal antigen or culture positivity, none of which fit an afebrile, HIV-negative patient with positive malaria serology. D. Visceral leishmaniasis: causes splenomegaly with pancytopenia and fever, and is not endemic in Papua New Guinea; it does not account for the strongly positive malaria serology. B. Schistosomal portal hypertension: produces splenomegaly via portal fibrosis with signs of portal hypertension (varices, ascites) and is linked to schistosome exposure, not to raised IgM or malaria serology. Key point: massive splenomegaly with markedly raised IgM and strongly positive malaria serology despite repeatedly negative films in a resident of a holoendemic area is the classic fingerprint of hyperreactive malarial splenomegaly.

Reference: Lalloo DG, Shingadia D, Bell DJ, et al. UK malaria treatment guidelines 2016. Journal of Infection 2016;72(6):635-649 (PHE/BIA endorsed UK guidance on malaria and its immunological syndromes, including hyperreactive malarial splenomegaly), https://www.journalofinfection.com/article/S0163-4453(16)00047-5/fulltext